1. Field of the Invention
The present invention relates in general to seat slide devices for motor vehicles, and more particularly, to seat slide devices of a type which can establish a latched engagement between upper and lower rails upon a vehicle collision or the like.
2. Description of the Prior Art
One of the seat slide devices of the above-mentioned type is shown in Japanese Utility Model Second Provisional Publication No. 57-24594.
The seat slide device of this publication comprises generally two lower rails which are secured to a vehicle floor, two upper rails which mount thereon a seat proper and are slidably engaged with the lower rails, a seat slide latching mechanism which latches the upper rails to the lower rails at desired fore-and-aft positions of the seat proper and a rail-disconnection inhibiting mechanism which establishes a latched engagement between the upper and lower rails upon application of great load to the rails due to a vehicle collision or the like.
The seat slide latching mechanism includes a plurality of lock openings which are formed in one of the lower rails and a latch bar which is held by one of the upper rails in a manner to be latchingly engageable with one of the lock openings.
The rail-disconnection inhibiting mechanism includes a plurality of stopper openings which are formed in a horizontal upper side part of each lower rail and a plurality of stopper pawls which are raised up from each upper rail and directed toward the apertured horizontal upper side part of the lower rail. When, due to a vehicle collision or the like, a great load is applied to the seat slide device in a direction to pull apart the upper and lower rails, the stopper pawls of the upper rails are brought into latching engagement with some of the stopper openings of the lower rails thereby suppressing disengagement of the upper rails from the lower rails.
However, due to provision of large number of openings in the lower rails, the above-mentioned conventional seat slide device fail to have a satisfied mechanical strength. In fact, at least one of the lower rails has not only the openings for the slide latch mechanism but also the openings for the rail-disconnection inhibiting mechanism, and thus the mechanical strength of this rail becomes poor.